Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$190.41	3.190%	$196.4841	$196.48	$196.50	$196.50
Purchase #2	$202.44	10.733%	$224.1679	$224.17	$224.15	$224.20
Purchase #3	$128.50	13.113%	$145.3502	$145.35	$145.35	$145.40
Purchase #4	$37.88	8.798%	$41.2127	$41.21	$41.20	$41.20
Purchase #5	$218.90	3.647%	$226.8833	$226.88	$226.90	$226.90
Purchase #6	$37.87	4.247%	$39.4783	$39.48	$39.50	$39.50
Purchase #7	$214.34	11.441%	$238.8626	$238.86	$238.85	$238.90
7 purchase totals =	$1,030.34		$1,112.4391	$1,112.43	$1,112.45	$1,112.60